CN100538432C - Wave length variable filter, wave length variable filter module and optical spectrum analyser - Google Patents

Abstract

The object of the present invention is to provide the optical device, wave length variable filter, wave length variable filter module and the optical spectrum analyser that when reducing driving voltage, have superior optical characteristics.Optical device of the present invention (1) possess across at interval with fixation reflex film (35) side of movable part (21) in the face of putting and be arranged on regularly first electrode (33) on the fixed part, with second electrode (43) that facing of fixation reflex film (35) opposition side put and relative fixed portion is provided with regularly that is positioned at movable part (21) across the interval, in first electrode (33) and second electrode (43), one electrode is brought into play function as the detecting electrode that is used for the electrostatic capacitance between detection and the movable part (21), another electrode as be used for and movable part (21) between produce potential difference (PD), between them, produce electrostatic attraction thus, make the drive electrode of the position of movable part (21) and/or posture change and bring into play function.

Description

Variable wavelength filter, variable wavelength filter module and spectrum analyzer

technical field

The invention relates to an optical device, a variable wavelength filter, a variable wavelength filter module and a spectrum analyzer.

Background technique

As an optical device, for example, a wavelength tunable filter (Optical Tunable Filter) that separates only light of a specific wavelength from light having a plurality of wavelengths is known (for example, refer to Patent Document 1).

For example, the variable wavelength filter of Patent Document 1 is in the shape of a plate, and the movable part displaceable in the thickness direction thereof is arranged approximately parallel to the supporting substrate, and the surface of the movable part on the supporting substrate side is in contact with the supporting substrate. Reflective films are respectively provided on the surfaces (opposite surfaces) on the side of the movable part.

Also, the driving electrodes are provided on the support substrate, and a potential difference is generated between the driving electrodes and the movable part, thereby generating electrostatic attraction between them, and displacing the movable part. The gap distance between the two reflective films is variable by the displacement of the movable part. Then, when light having a plurality of wavelengths enters the gap, only light having a wavelength corresponding to the distance of the gap is emitted to the outside due to interference.

In order to properly generate such interference, it is necessary to correctly set the distance between the movable portion and the supporting substrate, or to increase the parallelism between the movable portion and the supporting substrate. Therefore, it is necessary to provide a plurality of drive electrodes, and to provide a plurality of detection electrodes on the supporting substrate to correspond thereto, and to detect the parallelism or The distance between the movable part and the supporting substrate.

However, in the variable wavelength filter of Patent Document 1, since the surface of the supporting substrate on the side of the movable part is a plane, the detection electrodes and the drive electrodes must be placed on the same plane. If the distance between the drive electrodes and the detection electrodes is small, , the coupling capacitance generated between them becomes large, making it difficult to perform the detection correctly.

In addition, if the distance between the driving electrode and the detecting electrode is increased in order to reduce the coupling capacitance generated between the driving electrode and the detecting electrode, the area of the driving electrode must be reduced for this reason, resulting in a lower driving voltage. Becomes high.

Patent Document 1: Specification of US Patent No. 6,747,775

Contents of the invention

An object of the present invention is to provide an optical device, a variable wavelength filter, a variable wavelength filter module, and a spectrum analyzer having excellent optical characteristics while reducing the driving voltage.

Such objects are achieved by the present invention described below.

The present invention provides an optical device, characterized in that it has:

a fixing part having a first light reflecting part;

having a second light reflection part opposed to the first light reflection part with a gap therebetween, and capable of being displaced relative to the fixed part to change the distance between the first light reflection part and the second light reflection part movable part;

a first electrode that faces a surface of the movable part on the side of the first light reflection part with a space therebetween, and is fixedly provided on the fixed part;

a second electrode that faces a surface of the movable portion opposite to the first light reflection portion with a gap therebetween, and is fixedly provided with respect to the fixed portion,

Of the first electrode and the second electrode, one electrode functions as a detection electrode for detecting a capacitance with the movable part, and the other electrode functions as a detection electrode for detecting a capacitance with the movable part. A potential difference is generated between them, thereby generating an electrostatic attraction between them, and functioning as a drive electrode that changes the position and/or orientation of the movable part,

Reflection is performed between the first light reflection part and the second light reflection part, and interference occurs, so that light having a wavelength corresponding to the distance between them can be emitted to the outside.

Thereby, the distance between the drive electrode and the detection electrode can be increased. As a result, the coupling capacitance generated between the drive electrode and the detection electrode can be reduced, the electrostatic capacitance between the movable part and the detection electrode can be detected with high precision, and based on the detection result, the movable part can be accurately displaced to the desired position. desired position and posture. In this case, the drive electrodes and the detection electrodes can be overlapped on a plane, so that the area of the drive electrodes can be increased, the drive voltage can be reduced, and the area of the detection electrodes can be increased to improve detection accuracy. Thus, the optical device of the present invention can reduce the driving voltage while obtaining superior optical characteristics.

In the optical device of the present invention, it is preferable that the electrostatic capacitance between the one electrode and the movable part is detected, and based on the detection result, a potential difference is generated between the other electrode and the movable part, thereby An electrostatic attractive force is generated between them to change the position and/or posture of the movable part.

Thereby, the movable part can be more accurately formed in a desired position and posture during use.

In the optical device according to the present invention, it is preferable that the first electrode or the second electrode is configured to be alternately switched between when functioning as the detection electrode and when functioning as the driving electrode.

Accordingly, the movable portion can be displaced both on the first electrode side and the second electrode side. Therefore, it is possible to increase the movable range of the movable part while reducing the stress generated in the movable part. As a result, it is possible to provide an optical device usable with light of a wide range of wavelengths.

In the optical device of the present invention, preferably, a plurality of the first electrodes and the second electrodes are respectively provided.

Thus, the distance between the first light reflection part and the second light reflection part and the parallelism between the first light reflection part and the second light reflection part can be controlled with high precision, so that the optical characteristics of the optical device are excellent.

In the optical device of the present invention, preferably, the number of the first electrodes is the same as the number of the second electrodes, and each first electrode is paired with each second electrode.

This makes it possible to easily set the drive voltage when changing the posture of the movable portion.

In the optical device of the present invention, preferably, the first electrode has a shape similar to that of the second electrode.

This makes it possible to more easily set the drive voltage when changing the posture of the movable portion.

In the optical device of the present invention, preferably, the size of the first electrode is the same as that of the second electrode.

Thereby, when changing the posture of the movable part, the driving voltage can be set more easily.

The optical device according to the present invention preferably has a supporting portion for supporting the movable portion, and a connecting portion that connects the movable portion and the supporting portion so that the movable portion can be displaced relative to the supporting portion, The movable part, the support part, and the connecting part are integrally formed.

Thereby, the attitude|position of the movable part with respect to a substrate can be stabilized more.

The optical device of the present invention preferably includes: a first substrate on which the movable portion, the support portion, and the connecting portion are formed; The second substrate; the third substrate fixedly arranged on the support portion on the other side of the first substrate, the first substrate, the second substrate and the third substrate An airtight space that allows the displacement of the movable part is formed between each of them, the first electrode and the first light reflection part are provided on the second substrate, and the third substrate The second electrode is arranged on the bottom.

Thereby, the contact between the movable part and the outside air can be blocked with a relatively simple structure, and the movable part can be stably driven.

In the optical device according to the present invention, preferably, a recess is formed on the surface of the second substrate on the side of the first substrate, and the first light reflection part and the first electrode are provided on the bottom surface of the recess. .

This eliminates the need to provide a spacer or the like between the first substrate and the second substrate, reduces the number of components, and forms an airtight space between the first substrate and the second substrate.

In the optical device according to the present invention, preferably, the concave portion has a first concave portion and a second concave portion formed on a bottom surface of the first concave portion, and the first electrode is provided on the bottom surface of the first concave portion outside the second concave portion. Above, the first light reflection part is disposed on the bottom surface of the second concave part.

Thus, even if the distance between the first light reflection part and the second light reflection part is increased to increase the wavelength of light that interferes, the distance between the first electrode and the movable part can be reduced and the driving voltage can be reduced. .

In the optical device according to the present invention, preferably, the first electrode is provided to surround the first light reflection part.

Accordingly, the posture of the movable portion with respect to the substrate can be easily and accurately detected.

In the optical device of the present invention, it is preferable that the first substrate is composed of silicon as a main material.

Thereby, stable driving can be performed, and an optical device having better optical characteristics and durability can be formed.

In the optical device according to the present invention, it is preferable that at least one of the second substrate and the third substrate is composed of glass as a main material.

Thereby, light can be incident between the first light reflection part and the second light reflection part from the outside via the second substrate and/or the third substrate, and the light can be reflected from the first light reflection part and the second light reflection part. Parts are emitted to the outside through the second substrate and/or the third substrate. Furthermore, visibility can be improved, and troubles such as foreign matter entering the inside of the device can be easily identified.

In the optical device of the present invention, it is preferable that at least one of the second substrate and the third substrate is composed of glass containing alkali metal ions as a main material.

Accordingly, when the first substrate is composed of silicon as the main material, the first substrate, the second substrate, and/or the third substrate can be easily and firmly bonded by anodic bonding.

In the optical device of the present invention, preferably, the first substrate is formed by processing a Si layer of an SOI wafer.

Accordingly, it is possible to provide relatively simple and highly accurate movable parts, support parts, and connecting parts.

In the optical device according to the present invention, it is preferable that at least one of the first light reflection portion and the second light reflection portion is formed of a dielectric multilayer film.

Thereby, light loss at the time of light interference between the 1st light reflection part and the 2nd light reflection part can be prevented, and an optical characteristic can be improved.

In the optical device of the present invention, the distance between the first electrode and the movable part and the distance between the second electrode and the movable part are preferably Roughly equal.

Thereby, when changing the position and/or posture of the movable part, it is possible to easily set the driving voltage.

In the optical device according to the present invention, it is preferable that the first electrode and the second electrode are arranged symmetrically across the movable part in a state where the potential difference is not generated.

Accordingly, when changing the position and/or posture of the movable portion, it is possible to more easily set the driving voltage.

The present invention provides a variable wavelength filter, characterized in that it has:

a fixing part having a first light reflecting part;

having a second light reflection part opposed to the first light reflection part with a gap therebetween, and capable of being displaced relative to the fixed part to change the distance between the first light reflection part and the second light reflection part movable part;

a first electrode that faces a surface of the movable part on the side of the first light reflection part with a space therebetween, and is fixedly provided on the fixed part;

a second electrode that faces a surface of the movable portion opposite to the first light reflection portion with a gap therebetween, and is fixedly provided with respect to the fixed portion,

Of the first electrode and the second electrode, one electrode functions as a detection electrode for detecting a capacitance with the movable part, and the other electrode functions as a detection electrode for detecting a capacitance with the movable part. A potential difference is generated between them, thereby generating an electrostatic attraction between them, and functioning as a drive electrode that changes the position and/or orientation of the movable part,

Reflection is performed between the first light reflection part and the second light reflection part, and interference occurs, so that light having a wavelength corresponding to the distance between them can be emitted to the outside.

Thereby, the distance between the drive electrode and the detection electrode can be increased. As a result, the coupling capacitance generated between the drive electrode and the detection electrode can be reduced, the electrostatic capacitance between the movable part and the detection electrode can be detected with high precision, and based on the detection result, the movable part can be accurately displaced to the desired position. desired position and posture. In this case, the drive electrodes and the detection electrodes can be overlapped on a plane, so that the area of the drive electrodes can be increased, the drive voltage can be reduced, and the area of the detection electrodes can be increased to improve detection accuracy. Thus, the variable wavelength filter of the present invention can reduce the driving voltage while obtaining superior optical characteristics.

The present invention provides a variable wavelength filter module, which is characterized in that it has:

a fixing part having a first light reflecting part;

having a second light reflection part opposed to the first light reflection part with a gap therebetween, and capable of being displaced relative to the fixed part to change the distance between the first light reflection part and the second light reflection part movable part;

a first electrode that faces a surface of the movable part on the side of the first light reflection part with a space therebetween, and is fixedly provided on the fixed part;

a second electrode that faces a surface of the movable portion opposite to the first light reflection portion with a gap therebetween, and is fixedly provided with respect to the fixed portion,

Of the first electrode and the second electrode, one electrode functions as a detection electrode for detecting a capacitance with the movable part, and the other electrode functions as a detection electrode for detecting a capacitance with the movable part. A potential difference is generated between them, thereby generating an electrostatic attraction between them, and functioning as a drive electrode that changes the position and/or orientation of the movable part,

Reflection is performed between the first light reflection part and the second light reflection part, and interference occurs, so that light having a wavelength corresponding to the distance between them can be emitted to the outside.

Thereby, the distance between the drive electrode and the detection electrode can be increased. As a result, the coupling capacitance generated between the drive electrode and the detection electrode can be reduced, the electrostatic capacitance between the movable part and the detection electrode can be detected with high precision, and based on the detection result, the movable part can be accurately displaced to the desired position. desired position and posture. In this case, the drive electrodes and the detection electrodes can be overlapped on a plane, so that the area of the drive electrodes can be increased, the drive voltage can be reduced, and the area of the detection electrodes can be increased to improve detection accuracy. Therefore, the variable wavelength filter module of the present invention can reduce the driving voltage while obtaining superior optical characteristics.

The invention provides a kind of spectrum analyzer, it is characterized in that, possesses:

a fixing part having a first light reflecting part;

having a second light reflection part opposed to the first light reflection part with a gap therebetween, and capable of being displaced relative to the fixed part to change the distance between the first light reflection part and the second light reflection part movable part;

a first electrode that faces a surface of the movable part on the side of the first light reflection part with a space therebetween, and is fixedly provided on the fixed part;

a second electrode that faces a surface of the movable portion opposite to the first light reflection portion with a gap therebetween, and is fixedly provided with respect to the fixed portion,

Of the first electrode and the second electrode, one electrode functions as a detection electrode for detecting a capacitance with the movable part, and the other electrode functions as a detection electrode for detecting a capacitance with the movable part. A potential difference is generated between them, thereby generating an electrostatic attraction between them, and functioning as a drive electrode that changes the position and/or orientation of the movable part,

Reflection is performed between the first light reflection part and the second light reflection part, and interference occurs, so that light having a wavelength corresponding to the distance between them can be emitted to the outside.

Thereby, the distance between the drive electrode and the detection electrode can be increased. As a result, the coupling capacitance generated between the drive electrode and the detection electrode can be reduced, the electrostatic capacitance between the movable part and the detection electrode can be detected with high precision, and based on the detection result, the movable part can be accurately displaced to the desired position. desired position and posture. In this case, the drive electrodes and the detection electrodes can be overlapped on a plane, so that the area of the drive electrodes can be increased, the drive voltage can be reduced, and the area of the detection electrodes can be increased to improve detection accuracy. Thus, the spectrum analyzer of the present invention can reduce the driving voltage while obtaining superior optical characteristics.

Description of drawings

FIG. 1 is an exploded perspective view showing an embodiment of an optical device (tunable wavelength filter) of the present invention.

FIG. 2 is a plan view showing the optical device shown in FIG. 1 .

Fig. 3 is a cross-sectional view along line A-A in Fig. 2 .

FIG. 4 is a diagram for explaining driving electrodes and detecting electrodes of the optical device shown in FIG. 1 .

FIG. 5 is a block diagram showing a configuration of a control system of the optical device shown in FIG. 1 .

FIG. 6 is a diagram for explaining a method of manufacturing the optical device shown in FIG. 1 .

FIG. 7 is a diagram for explaining a method of manufacturing the optical device shown in FIG. 1 .

FIG. 8 is a diagram for explaining a method of manufacturing the optical device shown in FIG. 1 .

FIG. 9 is a diagram for explaining a method of manufacturing the optical device shown in FIG. 1 .

FIG. 10 is a diagram for explaining a method of manufacturing the optical device shown in FIG. 1 .

FIG. 11 is a diagram showing an embodiment of the variable wavelength filter module of the present invention.

Fig. 12 is a diagram showing an embodiment of the spectrum analyzer of the present invention.

In the figure: 1—optical device (wavelength variable filter), 2—first substrate, 10—power circuit, 12—detection part, 13—switching part, 14—controlling part, 21—movable part, 22— Supporting portion, 23—connecting portion, 24—opening portion, 25—movable reflective film, 26—movable anti-reflective film, 27, 27a, 27b—opening portion, 3—second substrate, 31—first concave portion, 32—second recess, 33, 33a, 33b—first electrode, 34—insulating film, 35—fixed reflection film, 36, 36a, 36b—groove, 37, 37a, 37b—third recess, 38, 38a, 38b—drawing electrode, 39—fixed anti-reflection film, 4—third substrate, 41—recess, 43, 43a, 43b—second electrode, 44—insulating film, 42, 49—fixed anti-reflection film, 47a, 47b - opening, 3a, 4a - substrate (second substrate), 5, 6, 6A - mask layer, 51 - opening, 7 - conductive layer, 8 - SOI substrate, 81 - base layer, 82 - insulation Layer, 83—active layer (the first substrate), 9—resist layer, 100—wavelength variable filter module, 101, 104—optical fiber, 102, 103—lens, 200—spectral analyzer, 201—light Incident part, 202, 204—optical system, 203—light receiving element, 205—controlling part, 206—displaying part, G1—first gap, G2—second gap, G3—third gap, L—light.

Detailed ways

Hereinafter, the optical device, variable wavelength filter, variable wavelength filter module, and spectrum analyzer of the present invention will be described in detail based on preferred embodiments shown in the drawings.

1 is an exploded perspective view showing an embodiment of the optical device of the present invention, FIG. 2 is a top view of the optical device shown in FIG. 1 , FIG. 3 is a cross-sectional view along line A-A of FIG. FIG. 5 is a block diagram showing a configuration of a control system of the optical device shown in FIG. 1. FIG. In addition, in the following description, the upper side in FIG. 1 is referred to as "upper" and the lower side is referred to as "lower". "Down", "Right" for the right side, "Left" for the left side, "Up" for the upper side in Figure 3, "Down" for the lower side, "Right" for the right side, and "Left side" for the left side.

The optical device 1 shown in FIG. 1 is, for example, a variable wavelength filter that receives light and emits only light corresponding to a specific wavelength of the light (interference light) through interference. In addition, the optical device 1 can also be used as other optical devices such as an optical switch or an optical attenuator, for example.

As shown in FIGS. 1 and 3 , in such an optical device 1 , the second substrate 3 and the third substrate 4 are bonded via the first substrate 2 . Between the first substrate 2 and the second substrate 3, a first gap G1 for interfering light and a second gap G2 as an electrostatic gap for generating electrostatic attraction when the first gap G1 is reduced are formed. On the other hand, between the first substrate 2 and the third substrate 4, a third gap G3 is formed as an electrostatic gap for generating electrostatic attractive force when increasing the first gap G1. Here, the second gap G2 and the third gap G3 may each function as detection electrodes for detecting the electrostatic capacitance with the movable part 21 .

In such an optical device 1 , when light enters the first gap G1 , only light having a wavelength corresponding to the size of the first gap G1 is emitted due to interference. Hereinafter, each structure of the optical device 1 will be described in detail sequentially.

The first substrate 2 has light transmission and conductivity, and is made of, for example, silicon. Furthermore, the first substrate 2 has a movable portion 21 for making the first gap G1 between the first substrate 2 and the second substrate 3 variable, a supporting portion 22, and a movable portion that connects them so that the first gap G1 can be changed. 21 is a coupling portion 23 that displaces in the vertical direction relative to the support portion 22 . These are integrally formed by forming the opening 24 having a different shape in the first substrate 2 .

The movable portion 21 has a plate shape, is located substantially in the center of the first substrate 2 on a planar surface, and has a circular shape. Such a movable portion 21 is provided to face the second substrate 3 with a gap therebetween, and is displaceable in the thickness direction. In addition, it is needless to say that the shape, size, and arrangement of the movable portion 21 are not particularly limited to the illustrated shape.

The thickness (average) of the movable part 21 is appropriately selected depending on the constituent material, application, etc., and is not particularly limited, but is preferably about 1 to 500 μm, and more preferably about 10 to 100 μm.

In addition, on the surface of the movable portion 21 that faces the second substrate 3 (that is, the lower surface of the movable portion 21), as a second light reflection portion, a light reflection portion that reflects light with a relatively high reflectivity is formed. The movable reflective film (HR coating) 25 for light is formed with a movable reflector for suppressing light reflection on the surface opposite to the side facing the second substrate 3 (that is, the upper surface of the movable part 21). Anti-reflection film (AR coating)26.

As shown in FIG. 3 , the movable reflective film 25 multiple times reflects light incident on the first gap G1 from below the optical device 1 between the fixed reflective film 35 as a first light reflector described later. As shown in FIG. 3 , the movable anti-reflection film 26 is used to prevent the light entering the first gap G1 from below the optical device 1 from being reflected to the bottom of the figure at the interface between the upper surface of the first substrate 2 and the outside air.

The movable reflective film (dielectric multilayer film) 25 or the movable antireflection film 26 is not particularly limited as long as desired optical characteristics can be obtained, but is preferably composed of a dielectric multilayer film. That is, the movable reflective film (dielectric multilayer film) 25 or the movable antireflective film 26 is preferably constituted by alternately laminating high-refractive-index layers and low-refractive-index layers. Thereby, loss of light at the time of interference of light between the movable reflective film 25 and the fixed reflective film 35 can be prevented, thereby improving optical characteristics.

The material constituting the high refractive index layer is not particularly limited as long as it can obtain the optical characteristics required for the movable reflective film 25 or the movable antireflective film 26, but when it is in the visible light region or the infrared light region When used, _Ti2O , _Ta2O5 , niobium oxide, etc. are mentioned, and when used in _an ultraviolet region, _Al2O3 , _{HfO2 , ZrO2} , _ThO2, etc. are mentioned. In this embodiment mode, since the first substrate 2 is made of silicon, infrared light is used in the optical device 1 . Therefore, Ti ₂ O, Ta ₂ O ₅ , niobium oxide, or the like is preferably used as a material constituting the high refractive index layer.

The material constituting the low-refractive index layer is not particularly limited as long as it can obtain the optical characteristics required for the movable reflective film 25 or the movable antireflective film 26, and examples thereof include MgF ₂ and SiO _{2 .} wait. In particular, as a constituent material of the low refractive index layer, a constituent material mainly composed of SiO ₂ is preferably used.

The number and thickness of the high-refractive-index layers and low-refractive-index layers constituting the movable reflective film 25 and the movable antireflective film 26 are set according to required optical characteristics. Generally, when the reflective film is made of a multilayer film, the number of layers required to obtain the optical characteristics is 12 or more layers, and when the antireflection film is made of a multilayer film, the number of layers required for the optical characteristics is about 4 layers.

If the movable reflective film 25 has insulating properties, it is possible to prevent a short circuit caused by contact between the movable part 21 and the first electrode 33 . In other words, if an insulating film is provided on the surface of the movable portion 21 on the second substrate 3 side, short circuits caused by contact between the movable portion 21 and the first electrode 33 can be prevented.

In this case, since the movable reflective film 25 also serves as an insulating film, a short circuit caused by contact between the movable portion 21 and the first electrode 33 can be prevented with a simpler structure. In addition, since the movable antireflection film 26 also serves as an insulating film, a short circuit caused by contact between the movable portion 21 and the second electrode 43 can be prevented with a simpler structure.

The support portion 22 is formed to surround such a movable portion 21 , and the movable portion 21 is supported by the support portion 22 via the connection portion 23 .

A plurality of connecting parts 23 (four in the present embodiment) are provided at equal intervals in the circumferential direction around the movable part 21 . The connecting portion 23 has elasticity (flexibility), whereby the movable portion 21 is substantially parallel to the second substrate 3 with a gap therebetween, and can be displaced in the thickness direction (up and down). In addition, the number, position, and shape of the linking parts 23 are not limited to those described above as long as the movable part 21 can be displaced relative to the support part 22 .

In addition, openings 27a, 27b for accessing extraction electrodes 38a, 38a described later are provided on the first substrate 2 from the outside. The openings 27a and 27b also function as openings for pressure release to prevent a pressure difference from the outside in the space between the first substrate and the second substrate during the manufacturing process of the optical device 1 .

In such a first substrate 2 , it is preferable that the movable portion 21 , the support portion 22 , and the connection portion 23 are integrally formed. Thereby, the attitude|position of the movable part 21 with respect to the 2nd substrate 3 can be stabilized more.

In this case, if the movable part 21, the support part 22, and the connection part 23 are respectively composed of silicon as the main material, they can have more excellent optical characteristics and durability.

In particular, if the movable part 21, the supporting part 22 and the connecting part 23 are formed by processing one Si layer of the SOI wafer, then the movable part 21, the supporting part 22 and the connecting part 23 with higher precision can be formed relatively simply.

The second substrate 3 is bonded to the lower surface of the support portion 22 with respect to such first substrate 2 .

The second substrate 3 has light transmittance, and on the second substrate 3, a first recess 31 for forming a second gap G2 between the first substrate 2 and the second substrate 3 is formed on one side thereof, and a second recess 32 for forming a first gap G1 between the first substrate 2 and the second substrate 3 inside the first recess 31 .

The constituent material of such second substrate 3 is not particularly limited as long as it has light transmittance in relation to the wavelength of light used, for example, soda glass, crystalline glass, quartz glass, lead Glass, potassium glass, borosilicate glass, sodium borosilicate glass, alkali-free glass and other glass or silicon etc.

Among them, glass containing an alkali metal (mobile ion) such as sodium (Na) or potassium (Ka) is preferable as a constituent material of the second substrate 3 . Accordingly, when the first substrate 2 is made of silicon, for example, the first substrate 2 and the second substrate 3 can be easily and firmly joined by anodic bonding.

In particular, when bonding the first substrate 2 and the second substrate 3 by anodic bonding, the difference between the coefficient of thermal expansion of the first substrate 2 and the coefficient of thermal expansion of the second substrate 3 is preferably as small as possible, specifically , preferably 50×10 ^-7 °C ^-1 or less.

Therefore, even if the first substrate 2 and the second substrate 3 are exposed to high temperature during anodic bonding, the stress generated between the first substrate 2 and the second substrate 3 can be reduced, preventing the first substrate from Damage to the bottom 2 or the second substrate 3.

Therefore, as the constituent material of the second substrate 3, soda glass, potassium glass, sodium borosilicate glass, etc. are preferably used, for example, Pyrex Glass (registered trademark) manufactured by Corning Co., Ltd. is preferably used.

In addition, the thickness (average) of the second substrate 3 is appropriately selected according to constituent materials, applications, etc., and is not particularly limited, but is preferably about 10 to 2000 μm, and more preferably about 100 to 1000 μm.

The outer shape of the first concave portion 31 is circular, and it is disposed at positions corresponding to the movable portion 21 , the connecting portion 23 and the opening portion 24 . In addition, on the bottom surface of the first concave portion 31 , at positions corresponding to the outer peripheral portion of the movable portion 21 , an annular first electrode 33 and an insulating film 34 are laminated in this order. Then, the first electrode 33 is provided on the installation surface of the second substrate 3 on the movable portion 21 side.

The first electrode 33 has a substantially annular shape as a whole, and is composed of two first electrodes 33a and 33b that divide it into two. Furthermore, as shown in FIG. 5 , the first electrodes 33 a and 33 b are connected to the energization circuit 10 . Thereby, a potential difference can be generated between the first electrode 33 and the movable part 21 , and the capacitance between the first electrode 33 and the movable part 21 can be detected. In addition, the energization circuit 10 will be described in detail later.

Each of the first electrodes 33 a and 33 b is provided so as to surround the second concave portion 32 . Thereby, the electrostatic attractive force between each of the first electrodes 33a, 33b and the movable part 21 can be easily balanced. As a result, the posture of the movable portion 21 relative to the second substrate 3 can be further stabilized.

The constituent material of the first electrode 33 (the respective first electrodes 33a, 33b) is not particularly limited as long as it has conductivity, and examples thereof include metals such as Cr, Al, Al alloys, Ni, Zn, and Ti. , resin in which carbon or titanium is dispersed, polysilicon (polysilicon), silicon such as amorphous silicon, silicon nitride, transparent conductive materials such as ITO, Au, etc.

The thickness (average) of such first electrode 33 is appropriately selected depending on the constituent material, application, etc., and is not particularly limited, but is preferably about 0.1 to 5 μm.

The insulating film 34 has the same shape as the first electrode 33 and has a function of preventing a short circuit caused by contact between the movable part 21 and the first electrode 33 .

In such a space inside the first recess 31 , a second gap G2 is formed as an electrostatic gap (driving gap) for driving the movable portion 21 . That is, the second gap G2 is formed between the movable part 21 and the first electrode 33 .

The size of the second gap G2 (that is, the distance between the movable portion 21 and the first electrode 33 ) is appropriately selected depending on the application and the like, and is not particularly limited, but is preferably about 0.5 to 20 μm.

The outer shape of the second concave portion 32 is circular, substantially concentric with the first concave portion 31 , and has an outer diameter smaller than those of the first concave portion 31 and the movable portion 21 . In addition, a substantially circular fixed reflection film 35 is provided on the bottom surface of the second concave portion 32 (the surface of the second substrate 3 on the movable portion 21 side).

As described above, as shown in FIG. 3 , the fixed reflective film 35 is used to multiple times reflect light incident to the first gap G1 from below the optical device 1 between the movable reflective film 25 . That is, the fixed reflective film 35 can cooperate with the movable reflective film 25 to make light with a wavelength corresponding to the size of the first gap G1 (that is, the distance between the fixed reflective film 35 and the movable reflective film 25 ) put one's oar in. The size of the first gap G1 is larger than the size of the second gap G2.

The size of the first gap G1 is appropriately selected depending on the application and the like, and is not particularly limited, but is preferably about 1 to 100 μm.

As described above, if the fixed reflective film 35 is provided on the bottom surface of the second concave portion 32, it can be formed to correspond to the depth of the second concave portion 32 regardless of the distance between the first electrode 33 and the movable portion 21. And the wavelength band used. Therefore, even if it is set to a wavelength band that can be used in various ways, the driving voltage can be reduced.

In addition, the second concave portion 32 may also be omitted. In this case, the first electrode may be provided on substantially the entire bottom surface of the first concave portion 31 and the fixed reflective film 35 may be provided thereon without impairing the optical characteristics of the optical device 1 . Thereby, the area of the detection electrode or the driving electrode can be increased, the detection accuracy of the capacitance between the movable part 21 and the detection electrode can be improved, or the driving voltage can be reduced. In addition, by using a conductive material as the constituent material of the fixed reflective film, the fixed reflective film can be provided on substantially the entire bottom surface of the first recess 31, and the movable reflective film can also serve as the first electrode (detection electrode or drive electrode). Accordingly, the area of the detection electrode or the driving electrode can be increased, the detection accuracy of the electrostatic capacity between the movable part 21 and the detection electrode can be improved, or the driving voltage can be reduced.

In addition, in order to lead out the first electrodes 33a, 33b to the outside, third recesses 37a, 37b and grooves 36a, 37b connecting the third recesses 37a, 37b and the first recess 31 are formed on the second substrate 3. 36b.

The depths of the groove portion 36a and the third recess portion 37a are substantially equal to the depth of the first recess portion 31, and the lead-out electrode 38a connected to the first electrode 33a is provided on their bottom surfaces. Similarly, the depths of the groove portion 36b and the third concave portion 37b are substantially equal to the depth of the first concave portion 31, and the lead-out electrode 38b connected to the first electrode 33b is provided on their bottom surfaces.

As the constituent material of the extraction electrode 38 (extraction electrodes 38a, 38b), the same material as that of the first electrode 33 can be used, and it is not particularly limited as long as it has conductivity, for example, Cr, Al, Al alloys, metals such as Ni, Zn, and Ti, resins in which carbon or titanium are dispersed, silicon such as polysilicon, amorphous silicon, silicon nitride, transparent conductive materials such as ITO, Au, etc.

In addition, the thickness (average) of the extraction electrode 38 is appropriately selected depending on the constituent material, application, etc., and is not particularly limited, but is preferably about 0.1 to 5 μm. Furthermore, the extraction electrode 38a is preferably integrally formed with the first electrode 33a, and the extraction electrode 38b is preferably integrally formed with the first electrode 33b.

In addition, a fixed antireflection film 39 is formed on the other surface of the second substrate 3 (that is, the surface opposite to the surface on which the first concave portion 31 and the like are formed).

As shown in FIG. 3 , the fixed anti-reflection film 39 is used to prevent light irradiated from below the optical device 1 toward the first gap G1 from being reflected to the bottom of the figure at the interface between the bottom of the second substrate 3 and the outside air. In addition, the structure of the fixed reflection film 35 or the fixed anti-reflection film 39 is the same as that of the movable reflection film 25 or the movable anti-reflection film 26 .

The third substrate 4 bonded to the first substrate 2 on the opposite side of the second substrate 3 also has light transmission. Further, a recess 41 for forming a third gap G3 between the first substrate 2 and the third substrate 4 is formed on one side of the third substrate 4 .

Then, a space allowing the displacement of the movable portion 21 is formed between the first substrate 2 , the second substrate 3 , and the third substrate 4 , and this space can be formed as an airtight space. Therefore, the contact between the movable part 21 and the outside air can be blocked with a relatively simple structure, and the movable part 21 can be stably driven. In addition, in this embodiment, the portion other than the movable portion 21 of the first substrate 2 and the second substrate 3 and the third substrate 4 constitute a fixed portion, while the movable portion 21 is movable.

In addition, in this embodiment mode, the fixed reflective film 35 and the first electrode 33 are provided on the bottom surface of the concave portion formed on the second substrate 3 as described in this embodiment mode, so the first substrate 2 and the second electrode 33 need not be provided. A member such as a gasket is provided between the two substrates 3 to reduce the number of components and form an airtight space as described above between the first substrate 2 and the second substrate 3 .

The constituent material of such third substrate 4 is not particularly limited as long as it has transmittance depending on the wavelength of light used, and the same constituent material as that of the second substrate 3 can be used. Material. Therefore, when glass containing an alkali metal is used as a constituent material of the third substrate 4 , the third substrate 4 and the first substrate 2 can be bonded by anodic bonding similarly to the second substrate 3 .

If at least one of the second substrate 3 and the third substrate 4 is made of glass as the main material, light can be incident on the fixed reflection film from the outside through the second substrate 3 and/or the third substrate 4. 35 and the movable reflective film 25, or light is emitted from between the fixed reflective film 35 and the movable reflective film 25 through the second substrate 3 and/or the third substrate 4 to the outside.

In addition, the thickness (average) of the third substrate 4 is appropriately selected according to constituent materials, applications, etc., and is not particularly limited, but is preferably about 10 to 2000 μm, and more preferably about 100 to 1000 μm.

The concave portion 41 has a circular outer shape, and is disposed at positions corresponding to the movable portion 21 , the connecting portion 23 , and the opening portion 24 similarly to the first concave portion 31 . In addition, the depth and outer diameter of the recessed portion 41 are substantially equal to the depth and outer diameter of the first recessed portion 31 . In addition, on the bottom surface of the first concave portion 31 , an annular second electrode 43 (second electrode) and an insulating film 44 are sequentially stacked at positions corresponding to the outer peripheral portion of the movable portion 21 . Then, the second electrode 43 is provided on the installation surface of the third substrate 4 on the movable portion 21 side.

The second electrode 43 has a substantially annular shape as a whole, and is composed of two electrodes 43 a and 43 b that divide it into two, similarly to the first electrode 33 . Furthermore, like the first electrodes 33 a and 33 b , the second electrodes 43 a and 43 b are connected to the energization circuit 10 . Thereby, a potential difference can be generated between the second electrode 43 and the movable part 21 , and the capacitance between the second electrode 43 and the movable part 21 can be detected.

If at least one of the plurality of first electrodes and second electrodes is provided as described above, the posture of the movable part 21 can be changed or the posture of the movable part 21 can be detected. When changing the posture of the movable part 21, for example, approximately the same voltage may be applied to each of the first electrodes 33a, 34a or each of the second electrodes 43a, 43b to displace the movable part 21 so that the fixed reflection film 35 and the movable part 21 may be held. In addition, different voltages can be applied to each first electrode 33a, 33b or each second electrode 43a, 43b, so that the movable part 21 is displaced so that the movable reflective film 25 is relatively fixed. The membrane 35 is inclined. In addition, not only the position of the movable part 21 but also the posture of the movable part 21 can be detected.

In particular, in the present embodiment, since the plurality of first electrodes and the second electrodes are respectively provided, the posture of the movable portion 21 can be detected with higher accuracy. Also, for example, a potential difference may be generated only between the first electrode 33a and the second electrode 43b to displace a part of the movable part 21 toward the first electrode 33 and the other part of the movable part 21 toward the second electrode 43 . As a result, the posture of the movable portion 21 can be varied in a wider range.

In addition, the number of first electrodes is the same as the number of second electrodes, and each first electrode is paired with each second electrode. Therefore, when changing the posture of the movable part 21, the driving voltage can be easily set. In addition, when detecting the posture or position of the movable portion 21 , the configuration and processing of the detection portion 12 described later can be simplified.

In addition, since the shape of the first electrode 33 is similar to that of the second electrode 43 , it is possible to more easily set the driving voltage when changing the posture of the movable portion 21 . In addition, when detecting the posture or position of the movable portion 21 , the configuration and processing of the detection portion 12 described later can be simplified.

In addition, since the size (area) of the first electrode 33 is the same as that of the second electrode 43 , the driving voltage can be set more easily when changing the posture of the movable portion 21 . In addition, when detecting the posture or position of the movable portion 21 , the configuration and processing of the detection portion 12 described later can be simplified.

The constituent material of the second electrode 43 (the respective second electrodes 43 a and 43 b ) is not particularly limited as long as it has conductivity, and the same constituent material as that of the first electrode 33 can be used.

The thickness (average) of such second electrode 43 is appropriately selected depending on the constituent material, application, etc., and is not particularly limited, but is preferably about 0.1 to 5 μm.

The insulating film 44 has the same shape as the second electrode 43 and has a function of preventing a short circuit caused by contact between the movable part 21 and the second electrode 43 .

In such a space inside the concave portion 41 , a third gap G3 is formed as an electrostatic gap (driving pitch) for driving the movable portion 21 . That is, the third gap G3 is formed between the movable part 21 and the second electrode 43 .

The distance between the first electrode 33 and the movable part 21 (the second gap G2 ), and the second The distance (third gap G3 ) between the electrode 43 and the movable part 21 is substantially equal. Thereby, when changing the position and/or posture of the movable part 21, the drive voltage can be easily set. In addition, when detecting the posture or position of the movable portion 21 , the configuration and processing of the detection portion 12 described later can be simplified.

In this case, it is preferable to symmetrically arrange the first electrode 33 and the second electrode 43 with the movable portion 21 interposed therebetween in a state where the potential difference is not generated. Thereby, when changing the position and/or posture of the movable part 21, it becomes possible to set a drive voltage more easily. In addition, when detecting the posture or position of the movable portion 21 , the configuration and processing of the detection portion 12 described later can be simplified.

The size of the third gap G3 (that is, the distance between the movable portion 21 and the second electrode 43 ) is appropriately selected depending on the application and the like, and is not particularly limited, but is preferably about 0.5 to 20 μm.

In addition, on the bottom surface of the concave portion 41 , a substantially circular fixed antireflection film 42 is provided at the central portion thereof. That is, the second electrode 43 is provided on the bottom surface (installation surface) of the concave portion 41 in order to surround the fixed antireflection film 42 .

As shown in FIG. 3 , the fixed anti-reflection film 42 is used to prevent the light entering the first gap G1 from below the optical device 1 from being reflected to the bottom of the figure at the interface between the bottom of the third substrate 4 and the outside air. In addition, the structure of the fixed anti-reflection film 42 is the same as that of the movable anti-reflection film 26 .

In addition, openings 47a, 47b for accessing the extraction electrodes 38a, 38b from the outside are provided on the third substrate 4 . In addition, the lead-out of the said 2nd electrode 43 is taken out from the take-out part which is not shown in figure.

In addition, a fixed antireflection film 49 is formed on the other surface of the third substrate 4 (that is, the surface opposite to the surface on which the recessed portion 41 and the like are formed).

As shown in FIG. 3 , the fixed anti-reflection film 49 is used to prevent the light entering the third gap G3 from below the optical device 1 from being reflected to the bottom of the figure at the interface between the upper surface of the third substrate 4 and the outside air. In addition, the structure of the fixed anti-reflection film 49 is the same as that of the movable anti-reflection film 26 .

Here, the energization circuit 10 will be described in more detail based on FIG. 5 .

As shown in FIG. 5, this energization circuit 10 has a power supply unit 11 for applying a voltage to each electrode 33a, 33b, 43a, 43b, and a power supply unit 11 for detecting a voltage between each electrode 33a, 33b, 43a, 43b and the movable unit 21. Capacitance detection unit 12, switching unit 13 for switching the connection state between the electrodes 33a, 33b, 43a, 43b and the power supply unit 11 and detection unit 12, and controlling the power supply unit 11 and the switching unit based on the detection result of the detection unit 12. 13 drive control unit 14 .

The power supply unit 11 can selectively generate an arbitrary potential difference between the electrodes 33 a , 33 b , 43 a , 43 b and the movable unit 21 . That is, the optical device 1 can selectively apply a voltage to the first electrode 33 and the second electrode 43 to generate a potential difference between the first electrode 33 and/or the second electrode 43 and the movable part 21 . Thereby, the movable part 21 can be made into a desired position and posture more reliably.

The detection part 12 can independently detect between each electrode 33a, 33b, 43a, 43b and the movable part 21. Thereby, a potential difference can be generated between the respective electrodes 33a, 33b, 43a, 43b and the movable part 21 so that the movable part 21 takes a desired position and orientation.

The switching unit 13 can switch the connection state between the electrodes 33 a , 33 b , 43 a , 43 b and the power supply unit 11 and the detection unit 12 .

The control unit 14 controls the driving of the power supply unit 11 based on the detection result of the detection unit 12 . Thus, an arbitrary potential difference can be selectively generated between the electrodes 33a, 33b, 43a, 43b and the movable part 21 based on the capacitance between the electrodes 33a, 33b, 43a, 43b and the movable part 21. , to form a potential difference that makes the movable part 21 a desired position and posture.

In addition, the control unit 14 switches the connection state of the switching unit 13 in accordance with, for example, the set wavelength (first gap G1 ).

The operation (action) of the optical device 1 having such a configuration will be described.

The energization circuit 10 detects the electrostatic capacitance between one of the first electrode 33 and the second electrode 43 and the movable part 21, and based on the detection signal (detection result), in the first electrode 33 and the second electrode 43, A potential difference is generated between the other electrode and the moving part 21 .

More specifically, when the set wavelength is smaller than the first gap G1 when no voltage is applied, the first electrode 33 functions as a drive electrode, and the second electrode 43 functions as a detection electrode. In this case, a voltage is applied between the movable part 21 and the first electrode 33 through the energizing circuit 10, and the movable part 21 and the first electrode 33 are charged with opposite polarities to each other, and a Coulomb force (electrostatic force) is generated between the two. gravitational).

The movable part 21 moves (displaces) downward toward the first electrode 33 due to the Coulomb force, and stops at a position where the elastic force of the link part 23 and the Coulomb force are in balance. Accordingly, the sizes of the first gap G1 and the second gap G2 change. At this time, the posture (tilt) of the movable portion 21 is determined based on the balance between the voltage applied to the first electrode 33 a and the voltage applied to the first electrode 33 b.

In addition, when the set wavelength is larger than the first gap G1 when no voltage is applied, the first electrode 33 functions as a detection electrode, and the second electrode 43 functions as a driving electrode. A voltage is applied between the movable part 21 and the second electrode 43 by the energization circuit 10, and the movable part 21 and the second electrode 43 are mutually charged with opposite polarities, and a Coulomb force (electrostatic attraction) is generated therebetween.

The movable part 21 moves (displaces) upward toward the second electrode 43 due to the Coulomb force, and stops at a position where the elastic force of the link part 23 and the Coulomb force are in balance. Accordingly, the sizes of the first gap G1 and the second gap G2 change. At this time, the posture (tilt) of the movable portion 21 is determined based on the balance between the voltage applied to the second electrode 43 a and the voltage applied to the second electrode 43 b.

On the other hand, as shown in FIG. 3 , if light L is irradiated toward the first gap G1 from below the optical device 1, the light L passes through the fixed anti-reflection film 39, the second substrate 3, and the fixed reflection film 35, and is incident on the first gap G1. The first gap G1. At this time, the light L enters the first gap G1 with almost no loss due to the action of the fixed antireflection film 39 .

The incident light is repeatedly reflected (interfered) between the movable reflective film 25 and the fixed reflective film 35 . In this case, the loss of the light L can be suppressed by the movable reflective film 25 and the fixed reflective film 35 .

As mentioned above, when the light is repeatedly reflected between the movable reflective film 25 and the fixed reflective film 35, it does not meet the requirement of corresponding to the size of the first gap G1 between the movable reflective film 25 and the fixed reflective film 35. The light of the wavelength of the interference condition is rapidly attenuated, and only the light of the wavelength satisfying the interference condition remains, and is finally emitted from the optical device 1 . Therefore, by changing the voltage applied between the movable part 21 and the first electrode 33 and the second electrode 43, as long as the first gap G1 is changed (that is, the interference condition is changed), the intensity of the light passing through the optical device 1 can be changed. wavelength.

As a result of the interference of the light L, light (interference light) having a wavelength corresponding to the size of the first gap G1 passes through the movable reflection film 25, the movable part 21, the movable antireflection film 26, the fixed antireflection film 42. The third substrate 4 and the fixed anti-reflection film 49 are projected toward the top of the optical device 1 . At this time, due to the action of the movable antireflection film 26 and the fixed antireflection films 42 and 49 , the interference light is emitted to the outside of the optical device 1 with almost no loss.

In addition, in this embodiment, the light incident on the first gap G1 is emitted upward of the optical device 1 , but the light incident on the first gap G1 may be emitted downward of the optical device 1 .

In addition, in the present embodiment, light is made to enter from below the optical device 1 , but light may be made to enter from above.

In the optical device 1 described above, the first electrode 33 facing the surface of the movable part 21 on the side of the fixed reflection film 35 with a gap therebetween, and the surface opposite to the fixed reflection film 35 of the movable part 21 with a gap therebetween. Of the second electrodes 43 facing each other on the side, one electrode functions as a detection electrode for detecting the electrostatic capacitance between the movable part 21 and the other electrode functions as a detection electrode for generating capacitance between the movable part 21 and the movable part 21. A potential difference generates an electrostatic attraction between them, and functions as a drive electrode that changes the position and/or orientation of the movable portion 21 .

Thereby, the distance between the drive electrode and the detection electrode can be increased. As a result, the coupling capacitance generated between the drive electrode and the detection electrode can be reduced, the electrostatic capacitance between the movable part 21 and the detection electrode can be detected with high precision, and the movable part 21 can be accurately displaced based on the detection result. to the desired position and posture. In this case, the drive electrodes and the detection electrodes can be overlapped on a plane, so that the area of the drive electrodes can be increased, the drive voltage can be reduced, and the area of the detection electrodes can be increased to improve detection accuracy. Thus, the optical device 1 of the present invention can reduce the driving voltage while obtaining superior optical characteristics.

In particular, in the present embodiment, the capacitance between the one electrode and the movable part 21 is detected, and based on the detection result, a potential difference is generated between the other electrode and the movable part 21, whereby Electrostatic attraction is generated between them to change the position and/or posture of the movable part 21, so that the movable part 21 can be accurately formed into a desired position and posture during use.

In addition, the detection of the electrostatic capacitance as described above may be performed only at the time of calibration, and a potential difference is generated between the other electrode and the movable part 21 based on a preset conversion table or the like. In addition, in this case, all the electrodes 33a, 33b, 43a, and 43b may be used as drive electrodes after correction.

In addition, the first electrode 33 and the second electrode 43 may each function as a drive electrode for driving the movable portion 21 . That is, the first electrode 33 or the second electrode 43 is configured to alternately switch between when functioning as a detection electrode and when functioning as a driving electrode. Accordingly, the movable portion 21 can be displaced both on the first electrode 33 side and the second electrode 43 side. Therefore, it is possible to increase the movable range of the movable part 21 while reducing the stress generated in the movable part 21 . As a result, the optical device 1 can be used with light of a wide range of wavelengths.

In addition, the driving force required for the displacement of the movable portion 21 can be reduced, and as a result, the driving voltage can be reduced.

<Manufacturing method of optical device>

Next, an example of a method of manufacturing the optical device 1 will be described based on FIGS. 6 to 10 .

6 to 10 are diagrams for explaining the manufacturing process of the optical device 1 . In addition, FIGS. 6 to 10 show cross sections corresponding to the AA line cross section in FIG. 2 .

The manufacturing method of the optical device 1 according to this embodiment includes [A] a step of manufacturing the second substrate 3, [B] a step of bonding the SOI substrate to the second substrate 3, and [C] processing the SOI substrate to manufacture the first substrate 3. The step of substrate 2 , [D] the step of manufacturing third substrate 4 , and [E] the step of joining third substrate 4 and first substrate 2 . Each step will be described in order below.

[A] Fabrication of the second substrate 3

—A1—

First, as shown in FIG. 6( a ), a light-transmitting substrate 3 a is prepared as a substrate for forming the second substrate 3 .

As the substrate 3a, it is preferable to use a substrate having a uniform thickness without warpage or damage. As the constituent material of the substrate 3, the materials described in the description of the second substrate 3 can be used. As described above, as a constituent material of the substrate 3a, for example, glass containing an alkali metal (mobile ion) such as sodium (Na) or potassium (K) is preferably used. Therefore, in the following description, the case where glass containing an alkali metal is used as a constituent material of the substrate 3 a will be described.

—A2—

Next, as shown in FIG. 6(b), a mask layer 5 is formed (masked) on one side of the substrate 3a.

Examples of the material constituting the mask layer 5 include metals such as Au/Cr, Au/Ti, Pt/Cr, and Pt/Ti, silicon such as polysilicon and amorphous silicon, and silicon nitride. When silicon is used as a constituent material of the mask layer 5, the adhesiveness between the mask layer 5 and the substrate 3a is improved. When metal is used as a constituent material of the mask layer 5 , the visibility of the formed mask layer 5 is improved.

The thickness of the mask layer 5 is not particularly limited, but is preferably about 0.01 to 1 μm, and more preferably about 0.09 to 0.11 μm. If the mask layer 5 is too thin, the substrate 3 a may not be sufficiently protected, and if the mask layer 5 is too thick, the mask layer 5 may be easily peeled off due to the internal stress of the mask layer 5 .

The mask layer 5 can be formed by, for example, a chemical vapor deposition method (CVD method), a sputtering method, a vapor deposition method such as a vapor deposition method, a plating method, or the like.

—A3—

Next, as shown in FIG. 6( c ), an opening 51 having a planar shape corresponding to the planar shape of the first concave portion 31 , the groove portion 36 , and the third concave portion 37 is formed in the mask layer 5 .

More specifically, first, for example, by using a photolithography method, a photoresist is applied on the mask layer 5 , exposed to light, and developed to form a resist mask having openings corresponding to the openings 51 . Next, the mask layer 5 is etched through this resist mask, and after a part of the mask layer 5 is removed, the resist mask is removed. Thus, an opening 51 is formed on the mask layer 5 . Examples of this etching include dry etching using CF gas, chlorine-based gas, and the like, and wet etching using hydrofluoric acid+nitric acid aqueous solution, alkaline aqueous solution, and the like.

—A4—

Next, one surface of the substrate 3a is etched through the mask layer 5 to form a first recess 31, a groove 36, and a third recess 37 as shown in FIG. 6(d).

As this etching, a dry etching method or a wet etching method can be used, but the wet etching method is preferably used. Thereby, the formed first concave portion 31 can be formed into a more ideal columnar shape. In this case, as an etchant for wet etching, for example, a hydrofluoric acid-based etchant is preferably used. In addition, adding alcohol such as glycerin (particularly polyhydric alcohol) to the etchant can make the bottom surface of the formed first concave portion 31 extremely smooth.

—A5—

Next, after removing the mask layer 5, using the same method as the steps A2 and A3, as shown in FIG. Layer 6.

The method for removing the mask layer 5 is not particularly limited, and examples include wet etching using an aqueous alkali solution (for example, an aqueous solution of tetramethylammonium hydroxide, etc.), hydrochloric acid + aqueous nitric acid, hydrofluoric acid + aqueous nitric acid, or the like, and Dry etching using CF gas, chlorine-based gas, or the like.

In particular, as a method of removing the mask layer 5, if wet etching is used, the mask layer 5 can be removed efficiently with a simple operation.

—A6—

Next, using the same method as the above step A4, the substrate 3a is etched through the mask layer 6, as shown in FIG. The mask layer 6A corresponds to the opening of the planar shape. In addition, the formation of the mask layer 6A may be performed after the mask layer 6 is removed, or may be performed without removing the mask layer 6 .

—A7—

Next, as shown in FIG. 7( a ), a fixed reflection film 35 is formed on the bottom surface of the second concave portion 32 using the mask layer 6A.

More specifically, the fixed reflective film 35 is formed by alternately laminating the above-described high-refractive-index layers and low-refractive-index layers on the bottom surface of the second concave portion 32 .

As a method for forming the high refractive index layer and the low refractive index layer, for example, chemical vapor deposition (CVD) and physical chemical vapor deposition (PVD) are preferably used.

—A8—

Next, the mask layer 6 is removed as shown in FIG. 7( b ) by the same method as in the above-mentioned step -A5.

—A9—

Next, as shown in FIG. 7(c), on the surface of the side of the substrate 4 where the first concave portion 31 and the like are formed, the holes for forming the first electrodes 33a, 33b and the lead-out electrodes 38a, 38b, etc. are uniformly formed. Conductive layer 7.

As a method for forming conductive layer 7 , for example, chemical vapor deposition (CVD) and physical chemical vapor deposition (PVD) are preferably used.

In addition, as the constituent material of the conductive layer 7, the constituent material of the first electrode 33 can be used.

—A10—

Next, as shown in FIG. 7( d ), unnecessary portions of the conductive layer 7 are removed to form a first electrode 33 and the like, and an insulating film 34 is formed on the first electrode 33 . Furthermore, a fixed antireflection film 39 is formed on the surface of the substrate 4 opposite to the side on which the first concave portion 31 and the like are formed.

As a method of removing unnecessary portions of the conductive layer 7, the same method as that of the above-mentioned step A3 can be used.

In addition, as a method of forming the first electrode 33 , the same method as the method of forming the above-mentioned mask layer 5 can be used.

As a method of forming the fixed antireflection film 39, the same method as that of the above-mentioned fixed reflection film 35 can be used.

As described above, the second substrate 3 can be manufactured.

[B] Bonding of SOI substrate and second substrate 3

—B1—

First, as shown in Fig. 8(a), an SOI (Silicon on Insulator) substrate 8 is prepared.

This SOI substrate 8 is constituted by sequentially stacking three layers of a base layer 81 made of Si, an insulating layer 82 made of SiO ₂ , and an active layer 83 made of Si. In addition, instead of the SOI substrate 8 , an SOS (Silicon on Sapphire) substrate, a silicon substrate, or the like may be used.

The thickness of the SOI substrate 8 is not particularly limited, but the thickness of the active layer 83 is preferably about 10 to 100 μm.

—B2—

Next, before bonding the SOI substrate 8 and the second substrate 3 , as shown in FIG. 8( b ), a movable reflective film 25 is formed on the surface of the SOI substrate 8 on the active layer 83 side.

As a method of forming the movable reflection film 25 , the same method as that of the above-mentioned fixed reflection film 35 can be used.

—B3—

Next, as shown in FIG. 8(c), the SOI substrate 8 and the second substrate 3 are bonded.

As a bonding method between SOI substrate 8 and second substrate 3 , for example, anodic bonding, bonding with an adhesive, surface-activated bonding, bonding using low-melting glass, etc. can be used, but anodic bonding is preferably used.

In the case of using anodic bonding as a bonding method between the SOI substrate 8 and the second substrate 3, for example, first, connect the negative terminal of an unillustrated direct current power supply to the second substrate 3, and connect the positive terminal to the SOI substrate. The active layer 83 of the bottom 8 is connected. Next, while the second substrate 3 is heated, a voltage is applied between the second substrate 3 and the active layer 83 of the SOI substrate 8 . This heating facilitates the movement of positive ions of the alkali metal such as sodium ions (Na+) on the second substrate 3 . As a result, among the junction surfaces between the second substrate 3 and the active layer 83 , the junction surface on the second substrate 3 side is relatively negatively charged, and the junction surface on the active layer 83 side is relatively positively charged. As a result, the second substrate 3 and the active layer 83 are firmly bonded by a covalent bond in which silicon (Si) and oxygen (O) share electron pairs.

[C] Fabrication of the first substrate 2

—C1—

Next, as shown in FIG. 9( a ), etching or polishing is performed to remove the base layer 81 .

As this etching method, for example, wet etching and dry etching can be used, but dry etching is preferably used. In any case, when the base layer 81 is removed, the insulating layer 82 becomes a stopper. Since dry etching does not use an etching solution, damage to the active layer 83 opposite to the first electrode 33 can be well prevented. . Thereby, the yield at the time of manufacturing the optical device 1 can be improved.

—C2—

Next, as shown in FIG. 9( b ), etching is performed to remove the insulating layer 82 .

As this etching method, for example, wet etching and dry etching can be used, but wet etching using an etching solution containing hydrofluoric acid is preferably used. Thus, the insulating layer 82 can be easily removed, and the surface of the active layer 83 exposed by removing the insulating layer 82 can be made extremely smooth.

In addition, in the above-mentioned step B1, when a silicon substrate already having an optimum thickness required for performing subsequent steps is used instead of the SOI substrate 8, the steps C1 and C1 may not be performed. Thereby, the manufacturing process of the optical device 1 can be simplified.

—C3—

Next, as shown in FIG. 9( c ), a movable antireflection film 26 is formed on the upper surface of the active layer 83 .

As a method of forming the movable antireflection film 26, the same method as that of the above-mentioned fixed reflection film 35 can be used.

—C4—

Next, as shown in FIG. 9( d ), the resist layer 9 having openings corresponding to the openings 24 and 27 is formed.

As a method of forming the resist layer 9, the same method as that of the above-mentioned steps A2 and A3 can be used.

—C5—

Next, through the resist layer 9, the active layer 83 is etched by dry etching, especially ICP etching, and as shown in FIG. 9( e), after the opening 27 is formed, as shown in FIG. 9( f), An opening 24 is formed. Thereby, the movable part 21, the support part 22, and the connection part 23 are formed.

More specifically, when the active layer 83 is dry-etched through the resist layer 9, compared with the etching rate of the opening 27, the etching rate of each opening region of the opening 24 becomes slower due to the microloading effect. , so as shown in FIG. 9( e ), the formation of the opening 27 is completed prior to the formation of the opening 24 . At this time, since the opening 27 is formed above the third recess 37 communicating with the first recess 31 via the groove 36, the space between the active layer 83 and the second substrate 3 is opened to the outside, and the space and the outside are eliminated. pressure difference.

Here, the microloading effect refers to a phenomenon in which the etching rate decreases as the opening size becomes smaller. Therefore, as the opening 27 , such a size is adopted that the etching rate is faster than the etching rate of each opening region of the opening 24 . In this embodiment, as shown in FIG. 1 , the opening 27 is formed in a square shape whose length is one side wider than the opening width of each opening area of the opening 24 in the width direction. In addition, the size and shape of the opening 27 are not limited to the above-described configuration, and any configuration can be adopted as long as the etching rate of the opening 27 is faster than the etching rate of each opening region of the opening 24 .

If the micro-loading effect is utilized in this way, even if an etching process for forming the opening 27 is not separately provided, the same etching process can be used to form the opening 24 and the opening 27, and at the same time, the opening 27 and the opening 24 are sequentially formed. Forming it can simplify the manufacturing process.

After the opening 27 is formed, if the dry etching is further continued, the opening 24 is formed through as shown in FIG.

At this time, as described above, since the space between the active layer 83 and the second substrate 3 and the pressure difference outside are eliminated in advance before the movable portion 21 is formed on the active layer 83 (that is, before the opening portion 24 is formed). , Therefore, it is possible to prevent the connection portion 23 from being damaged when the opening portion 24 is formed.

Especially in this step, ICP etching is performed. That is, etching with an etching gas and formation of a protective film with a deposition gas are alternately repeated to form the movable portion 21 .

Examples of the etching gas include SF ₆ and the like, and examples of the welding gas include C ₄ F ₈ and the like.

In this step, the reason for performing anisotropic etching using a dry etching technique is as follows.

When using the wet etching technique, as the etching progresses, the etchant will invade between the active layer 83 and the second substrate 3 from the hole formed on the active layer 83, thereby removing the first electrode 33 or the insulating film 34. trouble. On the other hand, there is no such danger when the dry etching technique is used.

In addition, when isotropic etching is used, the active layer 83 is etched isotropically, and side etching occurs. In particular, when side etching occurs on the connecting portion 23 , the strength of the connecting portion 23 becomes weak and durability deteriorates. On the other hand, when anisotropic etching is used, since side etching does not occur, the control of the etching size is excellent, and the side surface of the connecting portion 23 is also formed perpendicular to the plate surface of the active layer 83, thereby improving the stability of the connecting portion 23. strength.

In addition, in the present invention, in this step, the movable portion 21, the supporting portion 22, and the connecting portion 23 may be formed using a method other than the above-described dry etching method, and a method other than the dry etching method may be used to form the movable portion 21, the supporting portion 22, and the connecting portion 23. Moving part 21, supporting part 22 and connecting part 23.

—C6—

Then, the resist layer 9 is removed, and as shown in FIG. 9(g), a structure formed by joining the first substrate 2 and the second substrate 3 is obtained.

[D] Process of manufacturing the third substrate 4

—D1—

First, as a substrate for forming the third substrate 4 , as shown in FIG. 10( a ), a substrate 4 a having translucency is prepared.

As the substrate 4a, similarly to the above-mentioned substrate 3a, it is preferable to use a substrate having a uniform thickness without warping or damage. As the constituent material of the substrate 4a, the materials described in the description of the second substrate 3 can be used in the same manner as the constituent material of the substrate 3a.

—D2—

Next, using the same method as A1 to A4 of the above-mentioned step [A], as shown in FIG. 10( b ), the recessed portion 41 and the openings 47 a and 47 b are formed.

—D3—

Next, the second electrode 43, the insulating film 44, and the fixed antireflection films 42 and 49 are formed as shown in FIG.

As described above, the third substrate 4 can be manufactured.

[E] Step of bonding the third substrate 4 to the first substrate 2

Next, the third substrate 4 obtained in the step [D] and the first substrate of the structure obtained in the step [C] are bonded by the same method as in B3 of the step [B]. 2.

Thus, as shown in FIG. 10( d ), an optical device 1 is obtained.

The optical device 1 (wavelength variable filter) as described above can be used, for example, in the manner shown in FIG. 11 or FIG. 12 .

FIG. 11 is a diagram showing an embodiment of a variable wavelength filter module of the present invention, and FIG. 12 is a diagram showing an embodiment of a spectrum analyzer of the present invention.

The variable wavelength filter module 100 shown in FIG. 11 is installed, for example, on an optical transmission path of an optical network such as a wavelength division multiplexing (WDM) optical transmission system. Such a variable wavelength filter module 100 includes an optical device 1 as the variable wavelength filter, an optical fiber 101 and a lens 102 for transmitting light to the optical device 1, and a lens for transmitting light emitted from the optical device 1 to the outside. 103 and optical fiber 104.

In such a variable wavelength filter module 100 , light having a plurality of wavelengths can be incident on the optical device 1 through the optical fiber 101 and the lens 102 , and only light of a desired wavelength can be extracted through the lens 103 and the optical fiber 104 .

Such a variable wavelength filter module 100 can reduce the driving voltage while having excellent optical characteristics.

In addition, the spectrum analyzer 200 shown in FIG. 12 is a device for measuring the spectral characteristics (relationship between wavelength and intensity) of light to be measured. Such a spectrum analyzer 200 includes a light incident portion 201 for incident light to be measured, the optical device 1 , an optical system 202 for transmitting the light to be measured incident into the light incident portion 201 to the optical device 1 , and receiving light emitted from the optical device 1 . The light receiving element 203 of the light, the optical system 204 that transmits the light emitted from the optical device 1 to the light receiving element 203, the control unit 205 that controls the drive of the optical device 1 and obtains the spectral characteristics based on the output of the light receiving element 203, and the display control unit 205 The display unit 206 of the calculation result.

In such a spectrum analyzer 200 , the light to be measured that enters the light incident portion 201 enters the optical device 1 via the optical system 202 . Next, the light emitted from the optical device 1 is received by the light receiving element 203 via the optical system 204 , and the intensity of the light is obtained by the control unit 205 . At this time, the control unit 205 obtains the intensity of light received by the light receiving element 203 while sequentially changing the interference conditions of the optical device 1 . Next, the control unit 205 displays information on the intensity of light of each wavelength (for example, spectral waveform) on the display unit 206 .

Such a spectrum analyzer 200 can reduce the driving voltage while having superior optical characteristics.

The optical device, variable wavelength filter, variable wavelength filter module, and spectrum analyzer of the present invention have been described above based on the illustrated embodiments, but the present invention is not limited thereto, and the structures of each part may be replaced with Arbitrary structures with the same function. In addition, other arbitrary structures may be added to the present invention.

In addition, by using the optical device 1, a wavelength-variable light source or a wavelength-variable laser can be realized.

In addition, in the above-described embodiment, the first gap G1 or the second gap G2 is formed by the first recess 31 , but the first recess 31 may not be formed, and the gap between the second substrate 3 and the first substrate 2 may be formed. A liner is arranged between them to form a first gap G1 or a second gap G2.

Claims (21)

1. wave length variable filter is characterized in that possessing:

Fixed part with first photo-emission part;

Have across at interval and opposed second photo-emission part of described first photo-emission part, thereby and can described relatively fixed part displacement change the movable part of distance between described first photo-emission part and described second photo-emission part;

Across at interval with the described first photo-emission part side of described movable part in the face of putting, and be arranged on first electrode on the described fixed part regularly;

Across at interval with the described first photo-emission part opposition side of being positioned at of described movable part in the face of putting, and second electrode that is provided with regularly of described relatively fixed part,

In described first electrode and described second electrode, one electrode is brought into play function as being used to detect the detecting electrode of the electrostatic capacitance between this electrode and the described movable part, another electrode is as being used for producing potential difference (PD) between this another electrode and described movable part, between this another electrode and described movable part, produce electrostatic attraction thus, make the drive electrode of the position of described movable part and/or posture change and bring into play function

Between described first photo-emission part and described second photo-emission part, carry out light reflection repeatedly, produce and interfere, thus can be between the outside be penetrated with them the light of the corresponding wavelength of distance.

2. wave length variable filter according to claim 1, wherein,

Detect the electrostatic capacitance between a described electrode and the described movable part, and, between described another electrode and described movable part, produce potential difference (PD), between them, produce electrostatic attraction thus, make the position and/or the posture change of described movable part based on this testing result.

3. wave length variable filter according to claim 1, wherein,

Described first electrode or described second electrode constitute, and alternately switch when bringing into play function when bringing into play function as described detecting electrode and as described drive electrode.

4. wave length variable filter according to claim 1, wherein,

Described first electrode and described second electrode are provided with a plurality of respectively.

5. wave length variable filter according to claim 4, wherein,

The number of described first electrode is identical with the number of described second electrode, and each first electrode and each second electrode are paired.

6. wave length variable filter according to claim 1, wherein,

The shape of described first electrode is the shape similar shapes with described second electrode.

7. wave length variable filter according to claim 6, wherein,

The size of described first electrode is big or small identical with described second electrode.

8. wave length variable filter according to claim 1, wherein,

Be used to support the support of described movable part and link the linking part that described movable part and described support can make the relative described support displacement of described movable part thereby have, described movable part, described support and described linking part are integrally formed.

9. wave length variable filter according to claim 8, wherein,

Have: first substrate that is formed with described movable part, described support and described linking part; Be fixedly set in second substrate of described support in the one side side of described first substrate; Be fixedly set in the 3rd substrate of described support in the another side side of described first substrate, described first substrate and described second substrate and described the 3rd substrate separately between, be formed with the airtight space of the displacement of allowing described movable part, described second substrate is provided with described first electrode and described first photo-emission part, and described the 3rd substrate is provided with described second electrode.

10. wave length variable filter according to claim 9, wherein,

Face in described first substrate side of described second substrate is formed with recess, and the bottom surface of described recess is provided with described first photo-emission part and described first electrode.

11. wave length variable filter according to claim 10, wherein,

Second recess that described recess has first recess and forms in the bottom surface of this first recess, described first electrode are arranged on the bottom surface of described first recess in the outside of described second recess, and described first photo-emission part is arranged on the bottom surface of described second recess.

12. wave length variable filter according to claim 11, wherein,

Described first electrode is set to surround described first photo-emission part.

13. wave length variable filter according to claim 9, wherein,

Described first substrate is that main material constitutes with silicon.

14. wave length variable filter according to claim 13, wherein,

In described second substrate and described the 3rd substrate is that main material constitutes with glass one of at least.

15. wave length variable filter according to claim 14, wherein,

In described second substrate and described the 3rd substrate is that main material constitutes with the glass that contains alkali metal ion one of at least.

16. wave length variable filter according to claim 9, wherein,

Described first substrate forms by a Si layer of processing SOI wafer.

17. wave length variable filter according to claim 1, wherein,

Constituting one of at least in described first photo-emission part and described second photo-emission part by the dielectric multilayer film.

18. wave length variable filter according to claim 1, wherein,

Under the state that does not produce described potential difference (PD), the distance between the distance between described first electrode and the described movable part and described second electrode and the described movable part about equally.

19. wave length variable filter according to claim 18, wherein,

Under the state that does not produce described potential difference (PD), described first electrode and described second electrode are symmetrical arranged across described movable part.

20. a wave length variable filter module is characterized in that, possesses any described wave length variable filter in the claim 1～19.

21. an optical spectrum analyser is characterized in that, possesses any described wave length variable filter in the claim 1～19.

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